This invention relates generally to safety systems and devices for ensuring the safety of workers while positioned on a roof or an elevated structure. More particularly, the present invention relates primarily to safety systems and devices for preventing construction workers and the like from accidentally falling from a roof or a structure during the construction process.
Lifelines which may be retractable and various safety rails have been conventionally employed as safety devices in connection with the construction and maintenance of roofs and decks. In conventional safety systems to which the invention relates, lifelines are directly or indirectly securely anchored to a fixed structure and connect with a safety belt or harness worn by the worker. The extendable length of the lifeline is effectively restricted so that an accidental fall or rapid change of position of the worker is prevented by automatically locking the position of the lifeline, or for an auxiliary lifeline, the position of the auxiliary lifeline relative to a principal safety cable. One of the critical problems which is encountered in connection with such safety systems is anchoring the safety device to the roof structure so that the safety device remains effectively anchored should it be subject to severe loading due to an accidental fall or usage in an emergency situation. Providing a suitable anchoring structure is especially troublesome during construction or while the roof structure is only partially installed.
U.S. Pat. No. 5,143,171, which is assigned to the assignee of the present invention, discloses a lifeline system for a pitched roof. The system employs a frame for mounting the lifeline above the peak of the roof. The lifeline is received and secured in a shoe. Shoulders extend from the shoe and engage opposing sides of the pitched roof. Various anchor devices and hardware are disclosed for securing the system to the roof. In one disclosed embodiment, two roof-mounting pods are pivotally mounted to a shoe which receives the retractable lifeline housing.
For some construction projects, it is common for pre-cast concrete decking panels or planks to be lifted and positioned on a framework to form the floors or decks for the structure. Such pre-cast panels typically have widths on the order of 4 feet and thicknesses on the order of 8 inches. Opposed sides of the panel are slightly tapered and are traversed by groove-like channels which function as lifting notches. The panels are typically hollow core members manufactured from reinforced concrete. The panels are grabbed at the notches by self-loading tongs or hooks for lifting the panels into position.
It has long been recognized that fall protection of workers is a particular problem during the installation of pre-cast concrete deck panels because of the difficulty of providing an effective anchoring location for a lifeline. During conventional pre-cast panel construction techniques, it is highly desirable and necessary that the workers essentially be positioned near the leading edge of the deck as the panels are moved into position so that the next panel in sequence may be properly positioned.